Add inspection for missing Optional default values

common/src/test/kotlin/entity/optional/OptionalTest.kt

@@ -28,7 +28,7 @@ internal class OptionalTest {
 
 
     @Serializable
-    private class NullOptionalEntity(val value: Optional<String?>)
+    private class NullOptionalEntity(val value: Optional<String?> = Optional.Missing())
 
     @Test
     fun `deserializing null in nullable optional assigns Null`() {
@@ -82,4 +82,4 @@ internal class OptionalTest {
         }
     }
 
-}
+}

core/api/core.api

@@ -2451,6 +2451,7 @@ public final class dev/kord/core/cache/data/ApplicationCommandParameterData {
 	public static final field Companion Ldev/kord/core/cache/data/ApplicationCommandParameterData$Companion;
 	public synthetic fun <init> (ILjava/lang/String;Ljava/lang/String;Ldev/kord/common/entity/optional/OptionalBoolean;Ldev/kord/common/entity/optional/Optional;Ldev/kord/common/entity/optional/Optional;Lkotlinx/serialization/internal/SerializationConstructorMarker;)V
 	public fun <init> (Ljava/lang/String;Ljava/lang/String;Ldev/kord/common/entity/optional/OptionalBoolean;Ldev/kord/common/entity/optional/Optional;Ldev/kord/common/entity/optional/Optional;)V
+	public synthetic fun <init> (Ljava/lang/String;Ljava/lang/String;Ldev/kord/common/entity/optional/OptionalBoolean;Ldev/kord/common/entity/optional/Optional;Ldev/kord/common/entity/optional/Optional;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public final fun component1 ()Ljava/lang/String;
 	public final fun component2 ()Ljava/lang/String;
 	public final fun component3 ()Ldev/kord/common/entity/optional/OptionalBoolean;
@@ -2488,6 +2489,7 @@ public final class dev/kord/core/cache/data/ApplicationCommandSubcommandData {
 	public static final field Companion Ldev/kord/core/cache/data/ApplicationCommandSubcommandData$Companion;
 	public synthetic fun <init> (ILjava/lang/String;Ljava/lang/String;Ldev/kord/common/entity/optional/OptionalBoolean;Ldev/kord/common/entity/optional/Optional;Lkotlinx/serialization/internal/SerializationConstructorMarker;)V
 	public fun <init> (Ljava/lang/String;Ljava/lang/String;Ldev/kord/common/entity/optional/OptionalBoolean;Ldev/kord/common/entity/optional/Optional;)V
+	public synthetic fun <init> (Ljava/lang/String;Ljava/lang/String;Ldev/kord/common/entity/optional/OptionalBoolean;Ldev/kord/common/entity/optional/Optional;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public final fun component1 ()Ljava/lang/String;
 	public final fun component2 ()Ljava/lang/String;
 	public final fun component3 ()Ldev/kord/common/entity/optional/OptionalBoolean;
@@ -4740,6 +4742,7 @@ public final class dev/kord/core/cache/data/RegionData {
 	public static final field Companion Ldev/kord/core/cache/data/RegionData$Companion;
 	public synthetic fun <init> (ILjava/lang/String;Ldev/kord/common/entity/optional/OptionalSnowflake;Ljava/lang/String;ZZZLkotlinx/serialization/internal/SerializationConstructorMarker;)V
 	public fun <init> (Ljava/lang/String;Ldev/kord/common/entity/optional/OptionalSnowflake;Ljava/lang/String;ZZZ)V
+	public synthetic fun <init> (Ljava/lang/String;Ldev/kord/common/entity/optional/OptionalSnowflake;Ljava/lang/String;ZZZILkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public final fun component1 ()Ljava/lang/String;
 	public final fun component2 ()Ldev/kord/common/entity/optional/OptionalSnowflake;
 	public final fun component3 ()Ljava/lang/String;

core/build.gradle.kts

@@ -24,6 +24,8 @@ dependencies {
     api(libs.kord.cache.api)
     api(libs.kord.cache.map)
 
+    ksp(projects.kspProcessors)
+
     samplesImplementation(libs.slf4j.simple)
 
     testImplementation(libs.bundles.test.implementation)

core/src/main/kotlin/cache/data/ApplicationCommandData.kt

@@ -112,8 +112,8 @@ public fun ApplicationCommandGroupData(data: ApplicationCommandOptionData): Appl
 public data class ApplicationCommandSubcommandData(
     val name: String,
     val description: String,
-    val isDefault: OptionalBoolean,
-    val parameters: Optional<List<ApplicationCommandParameterData>>
+    val isDefault: OptionalBoolean = OptionalBoolean.Missing,
+    val parameters: Optional<List<ApplicationCommandParameterData>> = Optional.Missing(),
 )
 
 
@@ -133,9 +133,9 @@ public fun ApplicationCommandSubCommandData(data: ApplicationCommandOptionData):
 public data class ApplicationCommandParameterData(
     val name: String,
     val description: String,
-    val required: OptionalBoolean,
-    val choices: Optional<List<ApplicationCommandOptionChoiceData>>,
-    val channelTypes: Optional<List<ChannelType>>
+    val required: OptionalBoolean = OptionalBoolean.Missing,
+    val choices: Optional<List<ApplicationCommandOptionChoiceData>> = Optional.Missing(),
+    val channelTypes: Optional<List<ChannelType>> = Optional.Missing(),
 )
 
 

core/src/main/kotlin/cache/data/RegionData.kt

@@ -7,7 +7,7 @@ import kotlinx.serialization.Serializable
 @Serializable
 public data class RegionData(
     val id: String,
-    val guildId: OptionalSnowflake,
+    val guildId: OptionalSnowflake = OptionalSnowflake.Missing,
     val name: String,
     val optimal: Boolean,
     val deprecated: Boolean,

core/src/main/kotlin/cache/data/RoleData.kt

@@ -17,8 +17,8 @@ public data class RoleData(
     val name: String,
     val color: Int,
     val hoisted: Boolean,
-    val icon: Optional<String?>,
-    val unicodeEmoji: Optional<String?>,
+    val icon: Optional<String?> = Optional.Missing(),
+    val unicodeEmoji: Optional<String?> = Optional.Missing(),
     val position: Int,
     val permissions: Permissions,
     val managed: Boolean,

gateway/build.gradle.kts

@@ -11,6 +11,8 @@ dependencies {
     api(libs.ktor.client.websockets)
     api(libs.ktor.client.cio)
 
+    ksp(projects.kspProcessors)
+
     testImplementation(libs.bundles.test.implementation)
     testRuntimeOnly(libs.bundles.test.runtime)
 }

ksp-processors/src/main/kotlin/KSPUtils.kt

@@ -1,7 +1,7 @@
 package dev.kord.ksp
 
 import com.google.devtools.ksp.processing.Resolver
-import com.google.devtools.ksp.symbol.KSAnnotation
+import com.google.devtools.ksp.symbol.*
 import kotlin.reflect.KProperty1
 
 internal inline fun <reified A : Annotation> Resolver.getSymbolsWithAnnotation(inDepth: Boolean = false) =
@@ -18,3 +18,12 @@ internal class AnnotationArguments private constructor(private val map: Map<Stri
             get() = AnnotationArguments(arguments.associate { it.name!!.getShortName() to it.value!! })
     }
 }
+
+internal val KSReferenceElement.isClassifierReference: Boolean
+    get() = when (this) {
+        is KSDynamicReference, is KSCallableReference -> false
+        is KSClassifierReference -> true
+        is KSDefNonNullReference -> enclosedType.isClassifierReference
+        is KSParenthesizedReference -> element.isClassifierReference
+        else -> error("Unexpected KSReferenceElement: $this")
+    }

ksp-processors/src/main/kotlin/inspection/OptionalDefaultInspectionProcessor.kt

@@ -0,0 +1,52 @@
+package dev.kord.ksp.inspection
+
+import com.google.devtools.ksp.findActualType
+import com.google.devtools.ksp.processing.*
+import com.google.devtools.ksp.symbol.*
+import dev.kord.ksp.getSymbolsWithAnnotation
+import dev.kord.ksp.isClassifierReference
+import kotlinx.serialization.Serializable
+
+/** [SymbolProcessorProvider] for [OptionalDefaultInspectionProcessor]. */
+class OptionalDefaultInspectionProcessorProvider : SymbolProcessorProvider {
+    override fun create(environment: SymbolProcessorEnvironment): SymbolProcessor =
+        OptionalDefaultInspectionProcessor(environment.logger)
+}
+
+private val OPTIONAL_TYPES =
+    listOf("Optional", "OptionalBoolean", "OptionalInt", "OptionalLong", "OptionalSnowflake")
+        .map { "dev.kord.common.entity.optional.$it" }
+        .toSet()
+
+/**
+ * [SymbolProcessor] that verifies that every primary constructor parameter with `Optional` type of a [Serializable]
+ * class has a default value.
+ */
+private class OptionalDefaultInspectionProcessor(private val logger: KSPLogger) : SymbolProcessor {
+    override fun process(resolver: Resolver): List<KSAnnotated> {
+        resolver.getSymbolsWithAnnotation<Serializable>()
+            .filterIsInstance<KSClassDeclaration>()
+            .forEach { it.verifySerializableClassPrimaryConstructor() }
+
+        return emptyList() // we never have to defer any symbols
+    }
+
+    private fun KSClassDeclaration.verifySerializableClassPrimaryConstructor() {
+        primaryConstructor?.parameters?.forEach { parameter ->
+            if (parameter.hasDefault) return@forEach
+
+            val type = parameter.type
+            if (type.element?.isClassifierReference == false) return@forEach
+
+            val clazz = when (val declaration = type.resolve().declaration) {
+                is KSTypeParameter -> return@forEach
+                is KSClassDeclaration -> declaration
+                is KSTypeAlias -> declaration.findActualType()
+                else -> error("Unexpected KSDeclaration: $declaration")
+            }
+            if (clazz.qualifiedName?.asString() in OPTIONAL_TYPES) {
+                logger.error("Missing default for parameter ${parameter.name?.asString()}.", symbol = parameter)
+            }
+        }
+    }
+}

ksp-processors/src/main/resources/META-INF/services/com.google.devtools.ksp.processing.SymbolProcessorProvider

@@ -1 +1,2 @@
+dev.kord.ksp.inspection.OptionalDefaultInspectionProcessorProvider
 dev.kord.ksp.kordenum.KordEnumProcessorProvider

rest/build.gradle.kts

@@ -10,6 +10,8 @@ dependencies {
     api(libs.bundles.ktor.client.serialization)
     api(libs.ktor.client.cio)
 
+    ksp(projects.kspProcessors)
+
     testImplementation(libs.bundles.test.implementation)
     testImplementation(libs.ktor.client.mock)
     testRuntimeOnly(libs.bundles.test.runtime)